Field of the Invention
The present invention relates to a linear guide apparatus, and in particular, to an attaching device for an expandable bellows type dust cover which is mounted on a guide rail for preventing foreign particles, such as cutting chips or cutting oil, from depositing on a surface of the guide rail of a linear guide apparatus.
As shown in FIG. 18, a guide rail 1 of a linear guide apparatus has axial ball rolling grooves 3 formed in both lateral side surfaces. A slider 2 is straddlingly mounted on the guide rail 1 which has a continuous length. The slider 2 has ball rolling grooves (not shown) respectively opposing the ball rolling grooves of the guide rail 1. A plurality of balls are rollable inserted in the opposing ball rolling grooves.
These balls circulate through circulating routes formed in the slider 2 when the slider 2 moves on the guide rail 1 in the axial direction. When the slider 2 is removed from the guide rail 1, the balls are held within the ball rolling grooves in the slider 2 by a ball retainer. When the slider 2 is mounted on the guide rail 1, the ball retainer is accommodated in a retainer relief groove 3a formed in a groove bottom portion of the ball rolling groove 3 so that the ball retainer does not disturb the circulation of the balls.
The guide rail 1 is secured to a base of, for example, a machine tool, robot, measuring equipment, precision positioning table, etc., by a bolt. On the other hand, a member to be driven, such as a cutter table in the case of the machine tool, is screwed to the slider 2. With the movement of the slider 2, the member to be driven is linearly moved along the guide rail 1.
When an accurate linear movement is required especially, if foreign particles, such as dust, weld powder, cutting oil, or the like, are deposited on the upper surface 1a, or the ball rolling grooves of the guide rail 1, and if these foreign particles enter the inside of the slider 2, smooth rolling of the balls will be disturbed and the desired accuracy will not be insured. Furthermore, in a linear guide apparatus in which a dust seal made of rubber is attached to an end of the slider 2, the sliding movement of the slider becomes heavy, and the dust sealing has not been perfect.
Accordingly, in order to prevent deposition of foreign particles and to reduce a movement resistance, it has been carried out to cover the guide rail of the linear guide apparatus with a dust cover.
Dust covers of this type known in the art include, for example, a bellows 6 as shown in FIGS. 19 and 20. In attaching the bellows 6 to the guide rail 1, an attaching plate 6A is secured at one longitudinal end of the bellows 6 to an end face 1c of the guide rail 1 with bolts 7, and the other end of the bellows 6 is secured to an end face 2a of the slider 2 with screws 8. To this purpose, screw holes 9 are formed in the guide rail.
Accordingly, in the case of attaching the bellows type dust cover of the linear guide apparatus, it is necessary to form the screw holes (tapped holes) 9 in the end face 1c of the guide rail 1. However, guide rails are usually manufactured to have a long, standard, continuous length, and they are cut to a desired length in accordance with a user's request. As a result, problems are encountered in that it is not easy to work the tapped holes in the end face of the guide rail of a continuous length, it takes a lot of time to perform such work, and it hinders a reduction in product cost and delivery time.